Stereoscopic telemeter.



, A'. KNIG.

STEREOSGOPIC TELEMETER.

APPLGATION FILED NOV. 30, 1912.

Patented May 20, 1913.

/ @f A e1 /J/f/J t UNITED STATES PATENT OFFICE. ALBERT KNIG, OF JENA, GERMANY, ASSIGNOR TQ THE FIRMAOF CARL ZEISS, 0F

JENA, GERMANY.

STEREOSCOPIC TELEMETER.

Specification of Letters Patent.

Patented May 2o, 1913.

To all 'wh-om t may concern Be it known that I, ALBERT KNIG, a citizen of the German Empire, residing at Jena, Germany, have invented'a new and useful Stereoscopic Telemeter, of which the follow ing is a specification.

The present invention relates to a stereoscopic telemeter of the type, which has become known through thel German patent specification 162471, and is shown in that specification by Figure 6 and described on page 6, lines 93 to 115. To each of the oculars of this telemeter, which, as usual, lie between the objective lenses, ,a double image is p resented, the part-images of which are both erect, belong to opposite ends of the baseline and are contiguous to each other in Ia line of coincidence parallel to 'the base-line. The above-mentioned figure is, moreover, illustra-tive of the more general case, that the lower pair of part-images belongs to a different base-line than the upper one. Each double image is obtained by a' special separating prismsystem shown in the said ligure by crossed reflectors) -from a special pair of images, for which purpose two objective lenses are disposed at either end of the base-line.' For measuring purposes av deflecting device is provided, which in the case under consideration must' permit of altering the relative distance of the lower part-images and that of the upper partimages by lequal but opposite amounts. Although such a device is .not shown in the above-mentioned figure, it is` described in the text page 2, lines 43 to 51, and page 5, lines 3 to 8. When inthis well-known te- -lemeter through the actuation of the deflecting device coincidence has been obtained in the two double imagesfor an object atV any range (e. g. an infinitely great one), which object belongs partly ,to the lower and partly to the upper part-images, as is well known, in either double image that partof an object likewise divided by the line of coincidence, but iin-itely distant, which belongs to the lower part-image, lies displaced relatively to the part belonging fto the upper part-image in the direction parallel to the line of coincidence. This displacement is, for the above assumed case of the coincidence of in-nitely distant objects, the greater, rthe smaller the distance of the now observed object. Because in either double image the two partimages and, as is necessary for stereoscopic observation, the lower as well as the u per part-images belong to opposite ends o the base-line, in one double image the' lower part of this object lies displaced relatively to the upper part in the opposite sense to whatis the case in the other double image. The two images of the lower object-part therefore have another relative distance than those of the upper object-part. When observing stereoscop1cally,this has the wellknown elect, that the lower art ofthe object lies at a seemingly di erent distance than the upper part, while the relative position, whichl in either vdouble image the images of the upper and the lower objectpart occup does .not become perceptible.

rrom the just described manner, in which the part-images belong to the ends of the base-line it also follows, that one part of the spatial imageV is orthostereoscopic and the other pseudostereoscopic. When by actuating the deflecting device the relative distance of the two images of the lower objectpart is made equal to that of the two images of the upper one, the apparent distance of the lower object part also becomes equal to that of the upper one. The actuation of the delecting device, until this parity in the apparent distance 1s obtained, constitutes the measuring, when the instrument is used as a stereoscopic telemeter. As bythe ac-.

tuation of the deiiecting device the relative distance between the lower and that be. v

tween `the upper part-images is altered 4by equal but opposite amounts, .the relative distance between the two images of the lower object-part is equal to that ofthe upperone, when coincidence for the object is obtained. The instrument is therefore adapt-v ed to be used with either of its ocular-s asa 'coincidence telemeter, without requiring any altered adjustment. The new telemeter differs from this well-knownone by its two double images being derived from. one and the same separating prism system. For to its oculars are presented the two double images of a separating .prism system, of which images in uniocular telemeters usually only one is observed.,- while the other one, which is produced bythe so-called lostrays, remains unused, simlla-rly as there is derived from each of the separating prism systems of the above-mentioned stereoscopic telemeter, which is improved by this invention, besides the observed double image another one,

strument 1s explicitly mentioned on pageS,

vlines 51 to v53, only two objectives are employed, which receive the two ray-pencilsystems entering at the ends of the base-line. For obtaining the two double images from the pair of images formed by the objectives the field-lens of either of the two terrestrial angled oculars consists in this patent of two part-lenses, which form a wedge-edge with one another, and to either ocular isadded a second lens of reversion and a second reflecting prism. Further it is known from the patent specification 830,668 (page 2, lines 39 to 4 8), that in a telemeter having a separating prism one or the other, as may be desired,l of the double images obtained throughl this prism can be resented to the ocular. Finally from the ermau patent specification 231461 a separating prism telemeter is known, having two oculars, which, arranged at an angle to each other for the purpose of being used alternately, are directed toward the one and the other of the two double images of the separating prism.

If a air of measuring mark systems or a pair o single marks be disposed in the ocular focal planes, an arrangement known from stereoscopic telemeters, to each of the oculars of which a simple image is presented, and if this be done in such a manner that. the spatial scale of ranges r:omes to lie in the orthostereoscopic part of the field of View or that the spatial single mark lies entirely or partly in this part of the field 'of View, the instrument may also be used similarly to one of those well-known telemeters, viz., only with the orthostereoscopic part of the field of view. In the case of the spatial scale of ranges the distance of the object, whose range is to be found, may be read off directly on it, at a position of the deflecting device, fixed by the adjustment. -In the case of the spatial single mark the measurement is effected by bringing the obj ect, whose range is to be found, by means of the deflecting device into the same apparent distance as the said single mark.v With certain objects the application of' these metnods of measuring has an advantage; it is possible, e. g., to so measure the distance of punctual that remains unused. In the new telemeter along with the second separating yobjective lenses f and sources ofv light, without having need of the well-known devices, by which the image of the point of light is changed into a line.

. In the annexed drawing: Fig. 1 is a diagrammatic plan view of an' ocular prism system constructed according to the present in-4 vention. Figs. 2 and 3 are diagrammatic views in elevation and plan respectively of the optical parts of a telemeter constructed according to the invention. Fig. 4 shows the separating layer of this telemeter on an enlarged scale and is a section on line 4-4 of Fig. 2. Fig. 5 shows a separating layer of another type.

In Fig. 1 the separating prism system of the ocular prism system contains two separating layers lying at diferent heights and crossing one another. Two right-angled refleeting prisms a. having each a silvered hypotenusal surface, which is reflecting on both sides, are superposed in such a manner that these surfaces stand perpendicularly the one on the other and at an inclination of 45O to the direction of the base-line A A. For the protection of the separating layers each has cemented to it a right-angledrefleeting prism b. The mixed ray-pencil-system, which emerges from the front of the prisms a (its axial ray is indicated by a single arrow-head), is transmitted by means of t-WO right-angl right-hand ocular and furnishes a double image, the lower part-irage of `which belongs to the right-hand and the upper partimage to the left-hand end of the base-line. The mixed ray-pencil-system, which contains the rays, that would otherwise be lost, and emerges from the back of the prisms I) (its axial ray is indicated by a double arrowhead), is transmitted by being twice reected in a right-angled reflecting prism d to the left-hand ocular and furnishes a double image, the lower part-image of which belongs to the left-hand and the upper part-image to the right-hand end of the base-line.

1n the separating prism system, Figs. 2 and 3, a single separating layer reflecting on both sides is disposed. From the raypencil-systems entering at the -ends of the base-line two objective prisms e1 and e2 two images are produced by means of two these are transmitted to the separating layer goof a separating prism system g1, g2, after the right-hand ray-pencil-system has passed through a displaceable lass wedge h, which lndicates the deectmg device. The said separating layer occupies, as may be seen in Fig. 4, the upper half of the sectional surface and the axial rays impinge upon its separating edge z', which is parallel to the plane of triangulation.` Oneof the two double images produced by the separating prism system g1, g2, one or other of which images can 0ptionally be looked upon as the product of d reflecting prisms c to the iso the so-called lost rays,l is presented to the left-hand ocular p1, p2 by means of a collective lens le and a lens or reversion Z, between which arelectin prism m is disposed, as also by means o the three reflecting surfaces of two risms 'n and 0. The other double image 1s transmittedto the right-hand ocular p1, p2 by means of a collective. lens g and a lens of reversion consisting of two separate members r1, r2, as also by means of a reflecting prism s. The lenses g, r1 and 1-2 are so chosen as regards their powers that between r1 and r2 the rays in the ray-pencils follow parallel paths, in order, by displacing the right-hand ocular with the prism s and the lens r2 in a direction parallel to the base-line, to be able to adapt the distance between the oculars to the interocular distance of the observer.

In the example, Figs. 2 and 3, the lower part of the spatial image is orthostereoscopic, the upper part seudostereoscopic, each part occupying halij of the total field of View. When the separating layer go is formed, as in Fig. 5,' as a band parallel to the plane of triangulation, having two separating edges z', the part-images contributing toward the formation of the pseudostereoscopic part of thespatial image are bounded by these two separating edges, and those contributing toward the `formation of the orthostereoscopic part lie, divided into two pieces, below and above those contributing toward the formation of the pseudostereoscoplcv part; hence only in a smaller part of 4the spatial image the clearness is disturbed base-line is contained within the instrument,

two objective reflecting systems, one at either end of the said base-line, two objective lenses, two oculars and a separating prism system lying between the said objective lenses, the said separating prism system adapted topresent to either of the said oculars a double image, the part-images of which are both erect, belongto` opposite ends of the said base-line and are contiguousv to each other in a line of coincidence4 parallel to the said` base-line, and measuring means consisting of a delecting device adapted to alter the relativedistance between the lower part-images and that between the upper part-images by equal but opposite amounts.

ALBERT .KONIG- lVitnesses:

PAUL KRGER, RioHARD HAHN. 

